1. Field of the Invention
The present invention relates to the field of combustion ignition engines.
2. Prior Art
Compression ignition engines such as diesel engines are well known in the prior art. Such engines have a rather high compression ratio, and operate on the principle that the heat of compression will be high enough to cause ignition of diesel fuel when injected into the combustion chamber at or near the end of the compression stroke. Also known are compression ignition engine operating cycles that inject fuel into the combustion cylinder during the compression stroke well advanced of ignition to allow the fuel to mix well with the air in the cylinder, and to evaporate into a gaseous form before ignition. This is generally referred to as homogenous charge, compression ignition, or HCCI. HCCI works well in assuring complete combustion (lack of generation of soot or black engine exhaust). It also provides a more uniform temperature rise, avoiding local hot spots that result in the formation of NOX. However, it also has certain inherent limitations. Because of the uniform charge, ignition begins in multiple locations, almost simultaneously everywhere, at or near top dead center, before expansion during the power stroke has an opportunity to really begin. Consequently the temperature rise, while uniform, must be limited by limiting the amount of fuel injected during the compression stroke, limiting the power attainable to perhaps 20% to 30% of that which the engine is otherwise capable of.
Also known are camless engines, that is, engines using some form of engine valve operation other than a camshaft. One type of camless engine uses hydraulic engine valve control using electronically controlled valves for the engine valve control. See for example U.S. Pat. No. 6,739,293, the disclosure of which is incorporated herein by reference. Such valve control provides great flexibility in engine operation, whether in optimizing conventional engine operating cycles or executing advanced operating modes, such as in U.S. Patent Application Publication No. US 2007/0245982 A1, the disclosure of which is also incorporated herein by reference. In general, engines for operating using high pressure air injection have certain cylinders permanently dedicated to air compression and other cylinders permanently dedicated to combustion (power) cylinders.